Relay contact members



March 20, 1945.

T. L. WEYBREW RELAY CONTACT MEMBERS Filed Jan. 28, 1943 INVENTOR 779e/berf A .h/eybrew In .sa/afz'arz WITNESSES: 22% Z Patented Mar. 20,1945 RELAY con'raor MEMBERS Thelbert L. Weybrew, Edgcwood, Pa., assignorto Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa.,

Pennsylvania I Application January 28, 1943,

2 Claims. Cl. 200-166) My invention relates,

generally, to relays "and.

more particularly, to contact members for relays which are subject tovibration.

A magnetic-drag relay of the type Patent No. 2,209,368, issued July 30,1940, to C. C. Whittaker, may be utilized as a speed-indicating andover-speed protective relay on 9. Diesel engine for locomotive service.The overspeed contact members originally provided were of a usual typeconsisting of one stationary silver button on a screwpost and onemovable button on a fiat steel spring. 1 I

:Under normal conditions of operation these contact members remainclosed. The circuit through the contact members is opened under anoverspeed condition by motion of an insulated end of the relay arm. AllDiesel engines vibrate to some extent, the frequency and amplitudevarying with the speed and load, and the contact members originallyprovided were so disturbed by the vibration of the engine that theperformance of the relaywas not acceptable.

-1An object of my invention, generally stated, is to provide an improvedrelay which shall, .be

simple and efficient in operation and'which'may be economicallymanufactured and installed. I

.g A more specific object of my invention'is to overcome th effects ofvibration on the contact members of a relay. 1

Another object of my invention is to provide individual supportingmembers for relaycontacts which shall have the same natural period ofvibration.

Other objects of my invention will be explained fully hereinafter orwill be apparent to those skilled in the art.

In accordance with one embodiment of my invention, a pair of cooperatingcontacts of a relay comprises two duplicate contact spring members eachmade of a thin metal strip carrying a small contact button. The twocontact spring members are so mounted on an insulating base that'thebuttons face and bear against each other.v "p'lghe contact buttons donot separate underisevere vibration of varying frequency and amplitudebecause the two contact springs have the same natural period ofvibration and, thereforavibrate in unison.

For a fuller understanding of the nature and objects of the invention,reference may be had to the following detailed description, taken inconjunction with the accompanying drawing, in which:

Figure l is a view, partially in elevation and partially in section, ofa speed-responsive relay disclosedqin iii relay is utilized;

a corporation of Serial No. 473,82'l

embodying my invention, the contact-actuating arm of the relay beingshown in an intermediate position between zero speed and overspeed ofthe engine or other rotating device with which the Fig. 2 isa view,similar to Fig. 1, with the relay arm in the overspeed position;

Fig. 3 is an enlarged view in plan, of a pair of the relay contactmembers and their mounting base;

Fig. 4 is an enlarged view, in side elevation, or.

the contact structure shown in Fig. 3; and

Fig. 5 is an enlarged view, in end elevation, of the contact structure.

Referring to the drawing, and particularly to Figs. 1 and 2, the relayshown therein may be of the magnetic-drag type such as disclosed in theaforesaid Patent 2,209,368 which is suitable for utilization as aspeed-responsive relay. As described in the aforesaid patent, the relaycomprises'a shaft III which supports a rotatable disc (not shown) whichis disposed between a pair of rotating magnets (not shown) driven by aDiesel engine or other device with which the relay is utilized. Acontact actuating arm I I is securedto the shaft I0 and is normallybiased by a spring I2 to a position in which a contact member I3,carried by the arm I I, engages a fixed contact member I4 mounted on aninsulating support I5. One

' end of the spring I2 is atttached to an adjustable screw I6 and theother end is attached to an arm H which .is secured to the shaft I0.

As explained in the aforesaid patent, the contact members of the, relaymay be utilized to perform switching operations in response to the speedat which the rotating magnets are driven. In accordance with a principlewell known in the art, eddy currents are set up in the disc by the fluxproduced by the magnets and the rotation of the magnets causes amagnetic drag or torque on the disc which is proportional to the speedof rotation of the magnets. When the torque of the disc is suflicient toovercome the biasing force of the spring I2. the contact member I3 isdisengaged from the contact member I4 and the arm II is graduallyactuated toward the position shown in Fig. 1.

As the arm I I moves from the position shown in Fig. 1 to that shown inFig. 2 in response to an overspeed condition of the engine, the springI2 passes overcenter and the arm I I engages the end of a stop memberI8. Thus, the arm II is retained in the overspeed position by the springI2 until the relay is reset by actuating a plunger I9 which pushes thestop member I8 against a com pression spring 2| to actuate the arm l1past the overcenter position of the spring l2, thereby permitting thearm II to be returned to its normal position. It will remain in thisposition only if the torque has been reduced by a decrease in speedbelow that of the overspeed'condition. The relay is provided with a pairof overspeed contacts 22 which are normally closed but which areseparated by an insulating member 23 on the arm H in response to theoverspeed condition of the engine or other device with being utilized.

In order to overcome the efiects of vibration on the contacts 22, thesecontacts comprise two duplicate contact spring members 24 and 25"each ofwhich has a small silver button 26 mounted near one end thereof. Theother ends of the spring members 24 and 25 are so secured'to aninsulating base 21 by terminal bolts 28 and 29, respectively, that thebuttons 26 face and normally: bear against each other; he adjustablymounted by' a disposedln a slot 32 base 21.

bolt 3| which is As shown in Fig. 4, the spring'member 25 is ang'ularlydisposed on the'base 21, thereby permitting the insulating end 23 of thearm II to en'gagethe spring 24 when the contact arm is in thepositionshown in Fig. 2. In this manner the contact buttons 26 are separated,thereby interrupting; the electrical circuit through these Since the twocontact spring members 24 and 25 have the same natural period ofvibration, they vibrate in unison and, therefore, the contactbuttons 26:do not separate under severe vibration of varying frequency andamplitude. In this manner onepf the defects of the contact arrange mentpreviously utilized in relays of the present type is overcome, since'therelay isnot afiected by the vibrations of a Diesel engine or similardevice. Accordingly, the contacts 22 may be utilized tocontrol-electrical circuits, which will not be adversely affected by thevibration of the'engine and will be interrupted only inrespcnse to whichthe relay is- The base 21 may provided in one side ofthe indicated bythe 0P- ticularly' suitable for use on any relay which is subject toexcessive vibration.

From the foregoing description it is evident that I have'provided asimple and inexpensive contact mounting arrangement which is notadversely'afiected by vibration and overcomes the difficulties ofpreviously known relay contact structures.

Since numerous changes may be made in the above described constructionand different embodiments of the invention may be made without departingfrom the spirit and scope thereof, it is'intended that all mattercontained in the foregoing description or shown inthe accom panyingdrawing shall be interpreted as il1ustrative and not in a limitingsense.

I claim asmyinvention:

-1. In a relay, in combination, a pair of coopcrating" contactscomprising two resilient spring members each having a contact membermounted near one end thereof, said endxof each spring member beingunattached and free to vibrate, andmeans'for supporting the other endsof the spring members to normally hold said contact members inengagement, the free portions of said spring members being the samelength and having the same naturalperiod of vibration, whereby theyvibrate in unison.

2. In a relay, in combination, apair of cooperating contacts comprisingtwo resilient spring members each having a contact member mountednearone-end thereof, said end of each spring member being unattached andfree to vi"- brate, means for supporting the'other ends of thespringmembers, the free portions of said spring members being thesamelength and having the same natural period of vibration,.wherebytheyvibrate in unison and said contact members are normally held inengagement by said spring members, and means for engaging one of saidspring members to separate said contact members.

THELBERT- L. WEYBREW.

